Prove that java.util.Random isn't that random after all...

GuessRandom.java

import java.util.Random;
import java.util.concurrent.atomic.AtomicLong;

/**
 * in response to http://jazzy.id.au/default/2010/09/20/cracking_random_number_generators_part_1.html
 * <p>
 * the code on that website works 1 out of 4 times because, as mentioned by the
 * author itself, it isn't complete since he prefer to keep the code easier to
 * read and understand.
 * <p>
 * what i did is just add a 32 bit mask on 2nd random integer when it was cast
 * to long to ensure the bits remain the same regardless of positive or negative
 * number generated.
 * <p>
 * runnable code: http://ideone.com/pS58fs
 * 
 * @author zynick
 */
public class GuessRandom {

    // copied from Random source code
    private static final long multiplier = 0x5DEECE66DL;
    private static final long addend = 0xBL;
    private static final long mask = (1L << 48) - 1;

    public static void main(String[] args) {

        // give me 2 random integer
        Random rand = new Random();
        int i1 = rand.nextInt();
        int i2 = rand.nextInt();

        long l1 = i1;
        long mask32 = (1L << 32) - 1; // 32 bit masking
        long l2 = i2 & mask32;

        // find seed
        long shiftl1 = l1 << 16;
        long find = 0;
        for (long i = 0; i < 65536; i++) {
            find = shiftl1 + i;
            if ((((find * multiplier + addend) & mask) >>> 16) == l2) {
                System.out.println("seed found: " + find);
                break;
            }
        }

        // test seed
        AtomicLong found = new AtomicLong(find);
        int predict = next(32, found);
        predict = next(32, found);
        int expect = rand.nextInt();

        System.out.println("Predict: " + predict + "\nExpect : " + expect); // same!
    }

    // copied from Random source code
    protected static int next(int bits, AtomicLong seed) {
        long oldseed, nextseed;
        do {
            oldseed = seed.get();
            nextseed = (oldseed * multiplier + addend) & mask;
        } while (!seed.compareAndSet(oldseed, nextseed));
        return (int) (nextseed >>> (48 - bits));
    }
}